A plasma display panel (hereinafter referred to also as “PDP”) can be made thin and easily large-sized and further has characteristics such as light weight, high resolution, etc., and thus, it has attracted attention as a prospective candidate to be substituted for CRT as a display device.
PDP is generally classified into a DC type and an AC type, but its operational principle is one utilizing a light emission phenomenon due to gas discharge. For example, in the AC type, as shown in FIG. 11, cells (spaces) are defined by partition walls 3 formed between a transparent front substrate 1 and a rear substrate 2 facing each other, and in the cells, a Penning mixed gas such as He+Xe or Ne+Xe having a high ultraviolet light emission efficiency with little visual light emission, is sealed. And, in the cells, plasma discharge is induced to let phosphor layers 11 on the inner walls of the cells emit light thereby to form an image on a display screen.
In such a PDP display device, as electrodes to induce plasma discharge in pixels for forming an image, display electrodes 5 made of transparent conductive films and bus electrodes 6 on part of such display electrodes are formed by patterning on a transparent front substrate 1, and if necessary, black stripes 4 to separate pixels are formed by patterning. Further, on a rear substrate 2, address electrodes 7 are formed by patterning. And, in order to secure insulation between the display electrodes 5 and the address electrodes 7 to let plasma be generated constantly or to prevent the electrodes from erosion by plasma, the display electrodes 5, the bus electrodes 6 and the black stripes 4 are covered by a dielectric layer 8 and a MgO protective layer 9 (Patent Document 1 and Non-Patent Documents 1 and 2).
PDP of the DC type is different from the AC type in that the display electrodes are not covered by a dielectric layer and a protective layer.
Here, the above display electrodes 5 are desired to have a low resistance. Therefore, heretofore, it has been common to employ indium oxide containing tin oxide (hereinafter referred to also as “ITO”). ITO is commonly used, since it has a relatively low electric resistance and is excellent in transparency, electrical conductivity and patterning performance.
However, ITO is expensive. Further, in PDP of the AC type, if ITO is covered with a dielectric, the dielectric is likely to erode ITO, and the resistivity of ITO is likely to be thereby increased.
In order to improve the durability of ITO against such erosion by the dielectric, it is possible to adjust the components of the dielectric. However, in such a case, the original purposes of the dielectric, such as the insulation performance and the performance to prevent erosion from plasma, are likely to decrease at the same time. Therefore, a material to be substituted for such ITO and the corresponding method are strongly desired.
On the other hand, the respective patterns of the display electrodes 5, the bus electrodes 6 and the black stripes 4 as shown in FIG. 11, are usually sequentially separately formed by patterning by a photolithography/etching process. Accordingly, the production process is long and expensive, and a strong acid or a strong alkaline solution is employed, whereby the load to the environment is large. Therefore, a method which can be substituted for such a process is desired.
Further, it has been proposed to provide black stripes 4 to further improve the contrast thereby to make an image clearer, but they will be formed by a step separate from the steps for forming display electrodes 5, bus electrodes 6, etc., and thus the number of steps will correspondingly be increased.
Patent Document 1: JP-A-7-65727
Non-Patent Document 1: “Flat Panel Display Dictionary”, edited by Tatsuo Uchida and Hiraki Uchiike, published by Kogyochosakai, Dec. 25, 2001, p. 583-585
Non-Patent Document 2: “Flat Panel Display 2004 Practical Volume”, edited by Kenji Okumura, published by Nikkei BP, p. 176-183